Dom4j读写XML简介

要使用dom4j读写XML文档,需要先下载dom4j包,dom4j官方网站在 http://www.dom4j.org/
目前最新dom4j包下载地址:http://nchc.dl.sourceforge.net/sourceforge/dom4j/dom4j-1.6.1.zip 解开后有两个包,仅操作XML文档的话把dom4j-1.6.1.jar加入工程就可以了,如果需要使用XPath的话还需要加入包jaxen-1.1-beta-7.jar.

以下是相关操作:

一.Document对象相关

1.读取XML文件,获得document对象.

             SAXReader reader = new SAXReader();
             Document   document = reader.read( new File( " input.xml " ));

2.解析XML形式的文本,得到document对象.

             String text = " <members></members> " ;
             Document document = DocumentHelper.parseText(text);

3.主动创建document对象.

             Document document = DocumentHelper.createDocument();
             Element root = document.addElement( " members " ); // 创建根节点

二.节点相关

1.获取文档的根节点.

Element rootElm = document.getRootElement();

2.取得某节点的单个子节点.

Element memberElm = root.element( " member " ); // "member"是节点名

3.取得节点的文字

String text = memberElm.getText();

也可以用:

String text = root.elementText( " name " );

这个是取得根节点下的name字节点的文字.

4.取得某节点下名为"member"的所有字节点并进行遍历.

List nodes = rootElm.elements( " member " );

for (Iterator it = nodes.iterator(); it.hasNext();) {
    Element elm = (Element) it.next();
    // do something
}

5.对某节点下的所有子节点进行遍历.

             for (Iterator it = root.elementIterator();it.hasNext();) {
                 Element element = (Element) it.next();
                 // do something
             }

6.在某节点下添加子节点.

Element ageElm = newMemberElm.addElement( " age " );

7.设置节点文字.

ageElm.setText( " 29 " );

8.删除某节点.

parentElm.remove(childElm); // childElm是待删除的节点,parentElm是其父节点

9.添加一个CDATA节点.

         Element contentElm = infoElm.addElement( " content " );
         contentElm.addCDATA(diary.getContent());

三.属性相关.
1.取得某节点下的某属性

             Element root = document.getRootElement();    
             Attribute attribute = root.attribute( " size " ); // 属性名name

2.取得属性的文字

             String text = attribute.getText();

也可以用:

String text2 = root.element( " name " ).attributeValue( " firstname " );

这个是取得根节点下name字节点的属性firstname的值.

3.遍历某节点的所有属性

             Element root = document.getRootElement();    
             for (Iterator it = root.attributeIterator();it.hasNext();) {
                 Attribute attribute = (Attribute) it.next();
                 String text = attribute.getText();
                 System.out.println(text);
             }

4.设置某节点的属性和文字.

newMemberElm.addAttribute( " name " , " sitinspring " );

5.设置属性的文字

             Attribute attribute = root.attribute( " name " );
             attribute.setText( " sitinspring " );

6.删除某属性

             Attribute attribute = root.attribute( " size " ); // 属性名name
             root.remove(attribute);

四.将文档写入XML文件.
1.文档中全为英文,不设置编码,直接写入的形式.

XMLWriter writer = new XMLWriter( new FileWriter( " output.xml " ));
writer.write(document);
writer.close();

2.文档中含有中文,设置编码格式写入的形式.

             OutputFormat format = OutputFormat.createPrettyPrint();
             format.setEncoding( " GBK " );     // 指定XML编码        
             XMLWriter writer = new XMLWriter( new FileWriter( " output.xml " ),format);
            
             writer.write(document);
             writer.close();

五.字符串与XML的转换
1.将字符串转化为XML

String text = " <members> <member>sitinspring</member> </members> " ;
Document document = DocumentHelper.parseText(text);

2.将文档或节点的XML转化为字符串.

             SAXReader reader = new SAXReader();
             Document   document = reader.read( new File( " input.xml " ));            
             Element root = document.getRootElement();                
             String docXmlText = document.asXML();
             String rootXmlText = root.asXML();
             Element memberElm = root.element( " member " );
             String memberXmlText = memberElm.asXML();